Art of cleaning fabrics



June 24, 1947. G. P. HI -IBARD EIAL 2,422,897

2 2 v ART OF CLEANING FABRICS I Filed May 22,1943

IN VEN TOR-5 Patented June 24, 1947 ART OF CLEANING FABRICS George P.Hebard, Davenport, Iowa, and Herman E. Sheets, St. Paul, Minn.,assignors to American Machine and Metals, Inc., East Moline, 111., acorporation of Delaware Application May 22, 1943, Serial No. 487,992

2 Claims.

The invention relates to a novel process of washing fabrics.

More especially the invention relates to a process by which textiles maybe treated with soap and water to release soil present in the fabrics byagitating them a minimum length of time and using the minimum amount ofdetergent. The invention further contemplates setting up a routine ofprocedure which will assure, without any inspection of the clothes atthe end of the suds treatment, that when the appropriate succeedingsteps which include rinsing, bluing, souring, and at times bleaching arecarried out, the resulting laundered fabrics will be clean by acceptedstandards regardless of their degree of initial soil.

It is-an object of this invention to provide a novel process for washingfabrics in which the fabrics may be brought to such a condition duringthe washing operation that after subsequent treatments of washing,bluing and souring, and drying, predetermined standards of cleanlinesswill be attained while the amount of washing done and the quantity ofdetergent used will be the minimum required for the amount of soilpresent in the fabrics.

It is a further object to proportion the amount of washing anddetergents to the amount of soil present without the need of inspectingor testing the fabrics either before, during, or after the washingoperation, and without incurring the risk of having to repeat the entireprocess after the clothes have been rinsed and dried because the washingoperation itself had been inadequate.

In thewashing of clothes there is a very wide variation in the degree ofsoil present in successive batches. Consequently there are widevariations in the amount of detergent and in the amount of washingrequired to cleanse successive batches. This variation, however, cannotbe satisfactorily estimated by any inspection of the fabrics eitherbefore or during washing.

In commercial laundering it is extremely desirable to reduce the washingoperations to standards to be followed as a routine, but no satisfactorysystem has been available, since any fixed standard routine proposed, ifsufficient to insure satisfactory results on badly soiled clothes wouldbe wasteful of soap, water, and effort on less soiled clothes.

Furthermore, any standard routine suitable for less soiled clothes wouldnot be satisfactory for badly soiled clothes. Clothes would not reachany acceptable standard of cleaniness at the. end

of the whole launderingoperation, but onlyafter the rinsing, bluing andsouring, and bleaching operations are complete would this becomeevident. If, therefore, the first washing was inadequate, that factwould not be clearly manifest until the subsequent operations had beenperformed. To wash the clothes by an inadequate washing, therefore, isquite wasteful in that the washing must be repeated after the prolongedseries of subsequent steps have been performed.

It is, moreover, important that the washing be conducted as fast as isconsistent with attaining the results desired, and to this end it isimportant that in each washing stage, we use the maximum amount of soapwhich can be used efliciently. It is an object of this invention,therefore, to obtain a system by which each washing step may bestandardized and still utilize the maximum soap which it is capable ofbeing used efficiently.

It is an object of this invention to provide a standardized system ofwashing in which the amount of detergent and washing is automaticallyadjusted to the amount of soil so that, after all subsequent steps areperformed, the desired standard of cleanliness will be attained.

It is known that in washin more soap or detergent must be used in anytreatment of the clothes than is theroetically necessary to combine withthe soil present. This surplus produces a suds. In a horizontal axiswasher of the type generally used in commercial laundry practice thetumbling of the clothes whichare lifted out of the liquid by the ribsand fall back into the liquid traps air which tends to create bubbles inthe liquid. These bubbles increase the depth of the suds blanket. It isalso recognized that the reaction between the soap and all the soil inthe clothes is not instantaneous but requires time.

The soils present in the fabrics are of various types ranging from dirtparticles that do not adhere to the fabric and are readily washed offand soilslike sugar that go into true solution to compounds that mustflrstbe broken down into other compounds that will combine with the soapand go into a colloidal suspension. Some of the soil will combine withthe soap in a short time while other parts of the soil require a muchlonger time to combine. This is recognizedin practice by building up asuds blanket at the beginning of. each suds treatment, the suds blanket.providing a storage of detergent that permits the combination of .theless readily solu- 3 ble soil in the fabric with a detergent undercontinued agitation.

Commercial washers are normally operated at rated capacity and when thusoperated, the bath is always carried to a fixed liquid level. Inaccordance with this invention, it .has been discovered that we maydetermine another level somewhat above the liquid level, which may becalled the initial suds level, which is relativelyconstant for any givenmachine if the soap be admitted to the washer at a fixed rate. And thisis the level to which the blanket of suds rises when the amount of soapadded issubstantially the maximum that can be efiectively utilized inthat washing with clothes which bear that degree of soil. Thus thisinitial suds level coupled with the fixed rate at which the soap isadded permits an approximate adjustment of the soap to the soil in thegoods.

It is also possible to determine another suds l'evel considerably higherthan the initial suds level to which the blanket of suds will rise onlywhen substantially all of the soil has been removed or neutralized' byvthe soap to the point of leaving free soap in the solution. And thishigh suds level may be so coordinated with the initial suds level andthe rate at which soap is supplied that the arrival of the soap at thatlevel will very closely indicate the condition which the clothes willattain after they have been subjected to the subsequent operations.

While in the past soap and detergent have generally been fed by throwingin a bucket full of solid or liquid soap, the practice of this inventionrequires that the soap or detergent be fed in a formthat permitsimmediate solution in the bath of a. partat least of the soap, producingimmediate reaction with some of the soils. Furthermore it is necessarythat the soap or detergent, whether in solid or liquid form, be fed at auniform rate so that the suds blanket can build upduring the feeding ofthe soap and the soap feed stopped when the blanket reaches the sudslevel'referred. to above as the initial suds level. In practiceit isfoundyconvenient' to form a concentrated soap solution of a'uniformstrength and to feed this into the washer at a uniform rate. As the soapsolution begins to flow into the washer the agitation thereindistributes it throughout the bath and some action can take placebetween the soap just introduced and the soil immediately and While soapis still being fed to the washer.

Applicant has discovered that if the soap or detergent is fed to thewasher at a selected rate and in a readily soluble form some of the moresoluble soils will combine with the soap during the time the soap isbeing fed to the Washer. Accordingly, if the detergent is thus fed'at aselected rate until a given suds blanket is attained, the more solubleportion of the soil present will increase'the length of time required tobuild up the blanket by combining with some of the soap immediately.'This longer time of feeding soap will offset the, loss of soap in theinitial soap-soil reactions and also store in the suds a larger amountof detergent if the degree of soil is greater. This will be availableduring that agitation of the soiled fabric to combine with the soilslower to come off; 7 When the suds reaches the initial'suds level thesoap feed is shut off. It should be noted that feeding soap at a uniformrate at each operation until the suds level reaches a preset level isnot synonymous with feeding a uniform quantity of soap in eachtreatment. The amount fed is the amount needed to form the suds blanketplus the amount that is already combined during the feed- The last dropsof soap to be fed before the shutofi have not gone into solution. Whenthey do, they will temporarily build the suds blanket up above theinitial suds level. But as the agitation is continued for a fixed lengthof time, the additional soil going into solution lowers the sudsblanketbelow its initial blanket depth.

The initial suds level must be selected at such an elevation above thewater level that it will store enough soap to combine with the amount ofthe soils present that go into solution or suspension after the soapfeed has been cut off. It is the aim that at no time during any sudstreatment will the suds completely disappear causing redeposition of thesoil on the clothes.

The initial suds bath becomes so loaded with soil that no furthercleansing action can take place. As this bath is dropped out of'thewasher and the process repeated with successive clean baths a newcondition arises. After the soap feed has been out oil, the blanketdecreases in depth for a time, but as the soil in the fabrics becomesexhausted no more soap is taken out Of the suds.

The tendency for the agitation to beat in. air already alluded to willcause the suds blanket to build upagain.

It has been discovered that this increase in the depth of the sudsblanket after the soap feed has been cut off in any standardized-systemof washing treatments such as we have described, may be used-todetermine when further agitation with soap and water may be dispensedwith. Throughout the period of agitation after thefeed of soap has beenout off, air is being trapped in the soapy bath forming bubbles. Thecombination of some of the soap with'thesoil draws upon the suds blanketso that the suds blanket decreases in thickness, despite the airbeatenin, as the soil remaining in the fabrics combines with the bath.

The suds blanket will thus readily increase when the soil is exhaustedso that the final suds level" exceeds the initial suds level. Therefore,when the final suds level exceeds the level to which the initial sudslevel rose before shutting off the soap, the treatments with soap andwater may be discontinued.

Since there is considerable sloshing about in the washer, in thepreferred form there is a final suds level placed higher than theinitial suds level. This higher level must be reached before the sudstreatments are discontinued. A level to which the suds must rise isselected. Thi final suds level is placed sufficiently above the initialsuds level to make the indication positive, a.voiding anaccidentalorerroneousindication due to sloshing or. other causes.

This indication that. further treatment with soap maybe dispensed withis not in itself'an indication that the clothes are clean. Much of. thesoil still remains in the clothes. Some of it is in colloidal suspensionor solution in the liquid held within. the mass of the fabric bycapillarity. Some of it has settled on the clothes as a deposit in theform of a soap-soil compound generally referred to as a curd. Theclothes. contain three times their own Weight of water after draining sothat the amount of soil heldin suspension in the clothes may beconsiderable even after the bath is dumped.

Rather the arrival'of'the suds at the high final suds level is anindication that the remaining steps in the washing process whichconsistof ;a succession of rinses, generally hot rinses followed by coldrinses, and generally a bluing and souring treatmentwith a bleachingtreatment in addition may be carried through with the assurance thatacceptably clean clothes will be produced at the end of the treatmentWithout rewashing.

The high suds level is significant only near the end of any given periodof agitation. At times, if the rate of soap feed is quite rapid, anappreciable amount of soap is present in the washer at the moment offeed shutoff that has not yet had a chance to combine with the water. iIt may then happen that there is a rise in the initial suds level abovethe initial suds level at the time of shutoff for a short period untilthis excess suds has combined with the soil. The significant indicationis a high suds level persisting at the end of the period of agitation.

It has now been shown that an operating rou tine may be set up whereinthe liquid level is. always carried to the same elevation, a fixedquantity of clothes or fabrics introduced into the bath, the washeragitation started, a soap Or detergent solution of known characteristicsfed at a uniform rate until the suds reach the initial suds level. Thesoap supply is always shut off when this level is reached and theagitation continued for a fixed period. The dump valve is then openedallowing the dirty bath to, escape to the drain. The dump valve isclosed and the preceding procedure repeated. The agitation is thuscontinued in successive baths, each bath formed of the same quantity ofwater and having the same initial suds blanket, until the final sudsreach the final suds level. The soaptreatments are then discontinued andan established rinsing procedure is carried out.

The soil in the clothes is neither appraised before placing in thewasher nor are the clothes examined during the procedure. With waterlevel, suds levels, detergent type and concentration,

and detergent rate of feed once properly established to deliver clothesthat are clean according to any accepted standards of practice currentin that laundry, each successive batch treated, regardless of the amountof initial soil present, will conform to that same standard. 3

The rise of the suds to initial and final suds level respectively mayserve as a guide to the operator in the conduct of the washing process,the suds levels being observed through sight glasses.

In the preferred form illustrated in the drawing the arrival of the sudsat each level is arranged to close electric circuits that light pilotlights.

While the process has been illustrated as manually conducted, theinvention resides in the determination of when to stop feeding soap andwhen to stop the suds treatments to secure clean clothes at the end ofthe complete process regardless of whether performed automatically ormanually.

The single figure is a schematic showing of a washing machine arrangedto perform the novel process.

By referring to the drawing, it will be noted that the washing machineillustrated comprises a cylindrical receptacle l of conventional design,supported on saddles 2 and comprising end heads 3 and the cylindricalouter shell 4. This outer shell 4 has a door of conventional design,such as the door 5, arranged to slide on tracks 6.

Within the washer shell, a washing cylinder it is supported on trunnionsI I mounted within the end heads 3 by means of suitable bearingsprovided therefor. This cylinder is made up of end plates I2 and aperforated cylinder wall l3 having a door 14 therein of any desiredconstruction. The door may be of the sliding type mounted on tracks l5,or it could be pivoted or otherwise mounted. The cylinder I0 isadaptedto contain the clothes or other articles to be cleaned or washed,which clothes or articles may be introduced through the doors 5 and Mwhich come into alignment when the machine is at rest.

The machine may be driven by any type of power means, such as, forinstance, by means of a power drive pulley 20 mounted on one end of theshaft H and over which passes one or more belts 2| which in 'turn may bedriven by pulley .22 mounted on the end of the shaft of a reversingelectric motor 23. The motor may be controlled through switchesconnected through panel 24, such as, for instance, the starting switch26 and the stopping switch 21.

The washing machine is preferably equipped with means for introducingboth hot and cold water, such as, for instance, the water line as whichmay be employed for introducing cold water and the water line 40 whichmay supply hot water. The cold water line 30 is equipped with a valve 3!biased by a spring or other suitable means to closed position andadapted to be opened by a hand lever 32. In the form of the inventionhere illustrated, when the hand lever 32 is raised a dog 33, which ispivoted thereon, may be caused to engage or look over one of the teethconstituting a fixed stop 34 so as to hold the valve open to thedesired-degree. The pipe 40, provided for supplying hot water, is alsoequipped with a valve, such as that shown at 4|, adapted to be opened'bya hand lever 42 and, when opened, to be retained in open position by adog 43 engaging one of the teeth of the fixed stop 44. This construction permits either one or both valves to be opened to the desireddegree so that either or both hot and cold water can be admitted to thewashing machine through the inlet feeding pipe 45. i

The Water may be shut off manually after the same has reached thedesired level in the washing machine, or, as here illustrated, it may beshut off by means of mechanism which automatically shuts oil the waterwhen the same has reached a predetermined level. The mechanism for thispurpose, here illustrated, comprises a well 50 connected to the washingreecptacle by means of a pipe 5|. A float is mounted in the well 59connected to the stem 52 so that the float, which rises on the surfaceof the liquid, will cause the stem 52 to be elevatedan amount indicativeof the quantity of water in the washing machine. As shown in thedrawing, stem 52 is provided with a pair of laterally extending lugs 54,each of which is positioned to engage one of the dogs 33, 43,respectively, so that when the float with its stem 52 reaches apredetermined height, the lugs 54 will operate the dogs 33, 43 and willfree the valves so that they will automatically be moved to shutposition, and in this way out off the feeding of water.

The detergent or soap may be. employed in either solid or liquid form,as may be desired in any particular case. In the illustration heregiven, it is preferred that the detergents be employed asliquids orsolutions which may be contained in tanks 60, 6| and 62, respectively,which 7 are inturn connected to the washing receptacle through: pipesextending from. the bottomsoi each; and controlled,- respectively, byvalves 63:, 6.4. and: 65.

The suds level responsive means here illustrated are electrical incharacter and. comprise an electric circuit. 10, which includes a transeformer H. Connected across the circuit to. by suitable connecting wiresisany suitablev signalling or control mechanism 14 having a relay switch12 connected incircuit therewith. Furthermore, a second signal orcontrol mechanism I is connected across the circuit H1 by means ofconnecting wires: which include a relay switch 13. The mechanisms M: and1 5 may be lights, noise-making devices, relays or any other desiredmechanism which will operatewhen the switches 72 and 1:3, respectively,are closedand serve to give a signal to the operator, or toautomatically control'the operation of the mechanism as desired.

Connected to. the opposite side of the. transformer H is a circuit, oneside 80: of which. is grounded and the other side of which is connectedthrough solenoids 82' and 83; respectively, to electrodes 84 and' 85mounted in the end head 3 of the washing machine. These electrodes aremounted, respectively, ininsulating bushings 8S and 81 so that nocurrent can flow into the solenoids 82 and 83' exceptwhen thecorresponding electrode is short-circuited with the frame of themachine, such as by means of water within the washer.

The washing machine is also equipped with means for dumping the liquidcontents, such as a dump valve 99- mounted in the bottom of the washingreceptacle. This Valve may be of a conventional design and equipped withan operating lever 9 l. The valve may be closed by forcing the sameagainst its seat, and the same may be held shut bya dog 92 mounted onlever 9i which engages a portion of the frame. The dog isprovided with afoot pedal part 94 used in operating the dog. To open the valve, theoperator steps on the foot pedal 94, whereupon the dump valve moves toopen position. Directly below the dump valve there should be suitabledrain means 9? connected with the sewer or other outlet for disposing ofthe dirty waste liquids.

In the operation of the machine, the door 5t-of the receptacle and thedoor 14' of the cylinder are opened and a batch of dry, dirty clothes orother articles to be washed are introduced into the-interior' ofthewasher. The doors are thenclosed and the starting switch 26 is moved soas to start the motor and, in turn, to start the cylinder of the washingmachine in rotary motion. Water is promptly introduced into the-washingmachine and, according to the adjustment ofthe valves 3| and 4t relativeto each other, the water will be fed in at the desired temperature.Asthe-level of the water rises, it causes the float in the'well 59 torise and the stem 52' carried by the float to be elevated, with theresult that when the water in the washing-receptacle has. reached thedesired level, lugs 54, 54will. cause the dogs 38, 43 tobe lifted in amanner to free thevalvelevers 32 and 42 so that the valves canautomatically move to closed position. The effect of this operation isthat the water shuts off, and the water in the washer is thusestablished at'the desired level. Next, the operator adds soap accordingto the formula he may beusing, either aloneor in connection with alkali,by manipulating the measuring valves 63-.and 64. These measuring valvesare designed to .add' the; soapsolution at. a fixed predeterminedriatewhich'isxraster than the soap will be neutralized by the soil inthegarments so that an initial suds can rise, and which nevertheless. isslowenough so that the total quantity of soap maybe measured by thelength of time that the, soap. solution flows. before the initial sudshas reached itspredetermined depth. This. rate of flow once determined,may be heldconstant for any given machine and for given operatingconditions regardless-of the quantity of soil in'the clothes. As these:detergents. are addedto. the water, a suds. is formed, and this sudsgradually rises until itreaches the level of the lower 618C? trode 8:4.The result of the suds. level reaching the elevation of the electrode84. is that'a shorts circuitis created, and: a circuit is closed whichenergizes. the solenoid 82" which in turncauses therelay. switch 12 to.be. closed. This action causes the device M to be. energized, whereby asignal isgiven, or, if desired, the soap or detergent feeding mechanismis automatically shut ofi.

Ifv manual operation is. preferred, the operator, upon receiving thesignal given forth by the device 14, will in response thereto promptlyshut off the feed or detergent. After. this is accompl-ished theWashing; is continued fora fixed period, based on predeterminedstandards, of op.- eration, The length of this continued operation isdetermined: by the length of time required to get the; maximumpractical; value out of the soap which hasbeen added to the batch.

In accordance with this invention, it has been discovered thatwhenthequantity of soap has been adjusted to the soil; in the-manner abovedescribed that a fixed. period of subsequent agitation will, from thepractical point of View, get themaximum value from the operation,regardless of what the absolutev value may be of the amount of soil andthe absolute value of the amount of soap. He next steps. on the footpedal 94. and thereby releases the dump valve and discharges the. dirtywater and soap into the drain well 91. The duration of the sudsoperation so conducted will be, determined by a. clock or other suitabletiming means, or it can be conducted by means of clock, mechanism whichwill automatically open. the dump valve in the manner clearly understoodin this art.

After the machine is dumped, if the clothes need further washing thedump. valve, is again closed and the above-described operation is re,-peated, with'the same batch of clothes remaining in thewashing machine.

If the operation is. manually conducted, the operator will close thedump valve by stepping on the lever 91 and locking the same in closedposition with the. lever 94. Next, the operator introduces water throughvalves 3| and 4|, as previously described. On this second sudsoperation, detergent is again added at the predetermined rate until suchtime as the indicating device 14 indicates that the detergent feedshould be discontinued; A succession of such suds operations arethereupon conducted until such time as the clothes shall become clean.

When the clothes approach a condition which has been selected, on thebasis of predetermined standards as clean, the detergent which has beenadmitted during the detergent feeding period will be excessive inquantity relative to the amount of soil present, and consequently suchexcessive amount of detergent will be productive of a suds level whichcontinues to rise, as the washing operation is continued, above thenormal suds level. This new suds level will be built up to a heightwhich, when the clothes are sufficiently clean, will reach the elevationof the upper electrode 85; When this occurs, the solenoid 83 isenergized, which in turn causes the relay switch 13 to be closed and thesignalling or op-- erating mechanism 15 to be energized. In the case ofan automatic machine, the mechanism 15 would at this point cause thesuds operation. to be-discontinued and the washing procedure to go on toa suitable rinsing treatment or treatments. When manually operatedmechanism is employed, the mechanism 75 will indicate to the operator,by a suitable signal, that the wasliing is complete and he willthereupon discontinue the suds treatments and follow up with a suitablerinsing procedure. Any desired rinsing procedure is contemplated and maybe employed to finish the washing procedure. Also, blue and sourtreatments will be carried out in accordance with usual practice.

When the level of the contact at is properly adjusted in relation to thelevel of the upper con tact 85 and the detergent feed mechanism, anddepth of water employed, are all adjusted in proper relation to eachother, it will be found that the machine works well in accordance withthe principles of this invention and will function to indicate, orcontrol the machine, when the clothes are clean, so as to avoid furthersuds treatments.

By way of example, the following dimensions and washing conditions maybe taken as one embodiment of this invention which is found to servewell in practice.

A washer of the horizontal type, like that shown in the drawing, wasutilized, having a cylinder 42 inches in diameter and 84 inches long,and operating in a cylindrical receptacle slightly larger. The cylinderwas adapted to revolve at a speed of approximately 22 R. P. M. by meansof an electric motor which drove the washing cylinder severalrevolutions in one direction and then, by reversing the motor, drove thecylinder approximately the same number of revolutions in the oppositedirection.

To this washer approximately 225 pounds of dry, soiled clothes wereadded and hot Water was admitted until the water level was shut off atthe desired height by means of the water level shutoff mechanism. Whenthe proper water level was reached, detergent solution was introduced atthe rate of 1 gallons per minute. This solution is made by mixing 175pounds of soap and 175 pounds of meta-silicate with 700 gallons ofwater. At the same time, a gallon per minute of another detergent wasadded in the form of a solution which consists of 16 pounds of alkalidissolved in 50 gallons of water. The introduction of both of thesedetergents was started when the proper water level was reached, and bothwere shut off when the suds formed in the water reached the lowerelectrode 84. In this case, the lower electrode was placed from 4 to 5inches above the water level. After shutting off the supply of soap andother detergents, the washing Was continued for approximately 5 minutes,at the end of which time the dump valve was opened. In this case, theupper electrode was placed about 12 inches above the lower electrode 84.

The operation above described was repeated a number of times until suchtime as the clothes became clean and the suds level was caused to riseto the elevation of the upper electrode 85. When this upper level wasreached by the suds it was indicated by signal mechanism which told theoperator that the clothes were clean. In actual practice it was'foundthat the clothes were clean as indicated by the signalling mechanism. Inconsequence, the suds-operations were then discontinued and theprocedure completed by con-' ducting suitable rinsing treatments. In theabove mechanism, loads with varying degrees of soilas received in atypical commercial laundry were washed and, according to the amount ofsoil in each load, were given from 3 to 7 suds as the required number toproperly clean the same before the indication as to the cleanness of theload was given.

When reference is made herein to liquid level or .suds level, it is tobe understood that the level of the liquid as influenced by the presenceof suds therein is referred to. It is known that when a cleaning liquid,such as water containing. soap, is agitated air is whipped into theliquid and suds a're'formed, with the result that the volume of theliquid increases and the surface thereof is elevated. As additionalwater is not introduced to increase the Volume of the liquid, it isapparent that the suds blanket associated with the liquid is increasedin depthor thickness. It is the top of this blanket which is referred toas the suds level, although it is to be understood that there is nodefinite line of demarcation between the water and the suds, as theremight be between the suds and water in a stationary tub.

The apparatus of this invention is not to be limited to the formillustrated in the drawing, as the novelty herein relates to the sudslevel control mechanism operable for giving a signal or other actionsuch as that of setting into operation automatic control mechanism. Inconsequence, the invention is not to be limited by the foregoingdisclosure, but is to be construed according to the terms of theappended claims.

What is claimed is:

l. The process of removing soil from fabrics which comprises agitatingthe fabrics in a series of successive baths, the quantity of Water ineach bath bearing a fixed relation to the quantity of fabrics; addingsoap to each bath at the beginning of the agitation thereof at a fixedrate which is faster than the rate at which the soap can be neutralizedby the soil present with the quantities of water and fabrics presentuntil an initial blanket of suds is formed to a predetermined level;terminating the supply of soap when said blanket of suds is formed;continuing agitation until the entire period of agitation of each bathhas lasted for a fixed length of time; the rate of soap feed being suchthat upon the termination of the soap feed there is present in the bathsoap sufficient to produce a suds of at least a predetermined depthabove the initial suds level when the end of the period of agitation isreached if the fabrics are clean at that time, but insufiicient toproduce such a depth of suds at that time if the fabrics are not clean;and stopping the series of baths at the end of the first period ofagitation in which the suds is of at least said predetermined depthabove the initial suds level at the end of the period.

2. The process of removing soil from fabrics which comprises agitatingthe fabrics in a series of successive baths, the quantity of water ineach bath bearing a fixed relation to the quantity of fabrics; adding asolution of a suds forming detergent to each bath at the beginning ofthe agitation thereof at a fixed rate which is faster than the rate atwhich the detergent solution can of time; therrateefdetergentsolutionafeefl bein suchfthat thiamine-termination 'of the:detergen't solution feed ether-e vis ;present an the sbathcfletergent:slfletten .xsumcient to "ipmdube 'a "suds "of at 163313. 3.:predetemineii dep'th .aafzmve "the initial sufl'stlevel when the en clof ith'e period or ."agi-tation is reached if the fabrics "me-flean atthat timafbut'iinsufficient-to protiueeeueh a depth of seals Lat that:fime if thetfabrics feiremot clean; and -istapptn'gzsthe series #ofEbaths "at the end of the :m st 2 period -'of.1agi tation whichxthe'suds is of fat Ae'ast :said :predetemnmed Adepth .-falcrove the inltiel'Eufiszlevel rat the endof :the L period.

@EGRGE P. HEBARD.

REFERENCES -GIT ED fienowing references are of record-in the *1 thiseat-em:

"UNITED STATES ,PA'I'EN'IS Number Name Date 1,824,237 Schaum Sept. 22,1931 2,218,698 Clark Oct. 22, 1940 2,188,353 House Jan. '30, 19402,009,365 Wait July 23, 1935 1,954,261 Pierce Apr. 10, 1934 2,161,167Hushi-nsk-y June 6, 1939 2,273,769 Chayle Apr. '7, 1942 FOREIGN PATENTSNumber Country Date 481,721 Great Britain Mar. .16, 1938 OTHERREFERENCES Ro'ge'rs, Industrial'Chemistry,2nd ed., D. Van Nostrand, NewYork, 1*915,,page's'646-649. (Copy available in Div. 59.)

Gilmore, Sodium Metapho'sphat'e in Laundering, Ind. & Eng. Chem, Sept.1940, pages 1233- 1236. 8-137.

